Born to Be Good: The Science of a Meaningful Life

Sometimes vivid images produced by careful observation lead us astray. Such was the case in Charles Darwin’s analysis of the smile. Darwin kept detailed recordings of the development of the emotional lives of his children. In writing about the emergence of laughter, he discerned a reliable pattern. At around fifty days his children would begin to smile. Gradually, with age, in similar contexts such as tickling, which he resorted to as scientist and devoted father, he would see, about two months later, the rudimentary signs of laughter—“little bleating noises”—that systematically were released during exhalation.

From these transfixing observations, Darwin arrived at his thesis about the smile: that it is the first trace of the laugh. Given this assumption, he then answered—rightly, I believe—the question of the morphological origins of the smile. Why does the smile take its characteristic form of lips retracted upward and occasionally to the side? Why do we not signal a sense of amusement with an eyebrow flash, a cheek flicker or nostril flare, or any of the other thousands of possible configurations of facial muscles? Darwin’s answer is found in two claims. First, a nod to the principle of antithesis: We smile as a public offering of high spirits because the shape of the smile, with its curved movements upward, is the antithesis of the tightened lips, the lip corners pulled down, the bared teeth, of anger. The smile signals the antithetical state of its opposite expression, that of anger. The second observation is in keeping with Darwin’s analysis of the physical actions that facial expression are part of: The smile’s retraction of the mouth corners up, and occasionally, sideways, enables the kinds of exhalation and vocalizations seen in laughter.

Darwin’s thesis, then, is that the smile is the first stage of the laugh, the larva to the butterfly, the acorn to the oak tree. There is something deeply satisfying in this view. Perhaps the Greeks had it right, that there are indeed two swaths of human emotional life: the tragic realm, a serious, fate-altering spectrum of emotions like anger, fear, and sadness, associated with tragic losses, threats, and injustices; and a comedic realm, defined by playful, lighthearted emotion grounded in laughter. Perhaps all of our positive states—enthusiasm, hope, gratitude, love, awe—originate in our ability to take alternative perspectives upon our current state of affairs: a prerequisite of the laugh.

Parsimonious and pleasing as this may be, it’s wrong. When primatologist Signe Preuschoft put Darwin’s smile-as-laughter thesis to the test by examining when various nonhuman primates show smilelike and laughterlike displays, she found that these two displays occur in much different social contexts, and toward much different ends. The smile and the laugh originate in distinct slices of early primate life, and have subsequently followed separate evolutionary trajectories as they worked their way into the human emotional repertoire and our nervous systems.

SILENT BARED-TEETH AND RELAXED OPEN-MOUTH DISPLAYS

 

In her careful observations of primates, in particular several different macaque species, Preuschoft has catalogued numerous displays that convey affiliative, cooperative intent. These include pout faces and lip smacks (which Darwin wrote about—see chapter 2)—no doubt predecessors to the succor-seeking sulking we see in three-year-olds, and of course, the kiss. The most common affiliation-seeking displays in primates, and most central to our understanding of human smiling and laughter, are the silent bared-teeth display and the relaxed open-mouth display.

Across species, primates resort to the silent bared-teeth display to appease and to signal submissiveness, weakness, and social fear in contexts in which the likelihood of conflict and aggression is high, for example when nearing dominant primates. The silent bared-teeth display is most typically seen in submissive primates and is usually accompanied by inhibited posture, protective body movements such as shoulder and neck tightening, or hands hovering around the face for obvious defensive purposes. Thankfully, this display often short-circuits aggression, triggering reconciliation in the dominant monkey—affiliative grooming and embracing.